It is common in the medical field for a doctor and/or technologist to need to correlate an internal area/point of interest appearing on a radiographic image or a scan of a patient with a location on the skin surface of the patient. For example, if a doctor finds a suspicious internal mass on an image or scan, the doctor may decide to biopsy such mass, i.e., remove a portion of such mass for further testing. In order to do so, the doctor must determine where to insert a biopsy needle at the skin surface in order to contact the mass below. Once that determination is made, the insertion point is marked on the skin. Typically, this is done with a type of marking medium, e.g., a permanent or semi-permanent ink, or a small adhesive marker is attached to the skin.
One approach to identifying the area/point of entry at the skin surface of the patient is to place a radiopaque grid on the skin surface of a patient and radiographically image or scan, cross-sectionally, i.e., in a plane normal to the skin surface of the patient, through the grid and the patient's body underneath the grid. Resultant cross-sectional images or scans provide sequential cross-sectional slices of the imaged area, with the series of radiopaque grid lines appearing in the cross-sectional slices as a series of dots atop the skin surface. Each dot corresponds to a “y” coordinate point (see, for example, the reference coordinate system in FIG. 2). A doctor or technologist may then view the resultant imaging slices and determine the most appropriate slice(s) from which to identify the area/point of interest relative to the grid lines. A doctor or technologist may view the sequential cross-sectional imaging slices electronically, such as via a computer. Each subsequent cross-sectional imaging slice corresponds to a subsequent axial position or “x” coordinate point (see, for example, the reference coordinate system in FIG. 2) along the grid, i.e., the distance along the grid lines to which the respective slice corresponds. Accordingly, when the most appropriate slice(s) are determined by the doctor or technologist, the axial position of the slice(s) is identified on the grid. For example, the computer may shine a laser along the grid, such as, for purposes of example only, line A-A of FIG. 2, showing the axial position of the slice(s). Having determined the “x” coordinate point of the desired entry point on the skin, the “y” coordinate point for the desired entry point on the skin can be identified relative to the grid line dots using the selected imaging slice(s). However, in order to mark the skin, the grid must be removed. This can impede the accuracy of the placement of the mark, because once the grid is removed, the doctor or technologist no longer has the visible grid lines to use as a reference point.
Prior art attempts to solve the problem include grids that include plural openings, e.g., holes or slits in the grid at intersections of various grid lines so that a marking instrument, e.g., a marking pen, can be applied therethrough to mark the skin surface. One problem the inventors recognized with such a grid is that the underlying surface cannot be marked at substantially any point. Rather, the skin surface can only be marked at locations where one of the openings or slits in the grid is located. Thus, unless the desired marking point coincidentally coincides with one of the slits, the exact desired marking point cannot be marked. A doctor and/or technologist can only mark the skin surface at the closest slit to the identified area/point of interest. Such marking may be detrimentally inaccurate, depending on the size of the internal point of interest, making the biopsy more difficult.
Another prior art attempt to solve the problem is to use a porous grid material so that marking medium can be applied to the grid and pass through the grid to mark the skin. This permits a mark to be placed anywhere on the grid, and thus the skin. However, the inventors recognized that these grids still have several problems. Typically, grids are attached to the skin surface “SS” with an adhesive, such as a medical adhesive. These prior art devices utilize thin adhesive strips at opposing ends of the device to attach the device to an underlying surface. The device thus attaches to the underlying skin surface SS only at those opposing ends. Between the ends, however, the device may not conform to the contours of the skin but rather leave gaps between the device and skin and/or cause wrinkling of the device. Wrinkling and/or gapping of the device result in radiographic images or scans having grid lines or markings that are spaced away from the skin surface SS (as shown by some of the dots GL in FIG. 1). This gapping makes it more difficult for the technologist to correctly correlate the area of interest with the patient's skin surface SS because the references in the image, i.e., the dots GL, are not at the skin surface. In effect, the technologist must guess how to compensate for the gap between the gridlines and the skin when marking the skin. Gapping also increases the risk of inaccurate or incomplete marking. A gap or wrinkle can prevent marking medium placed on the grid from reaching the skin surface. Another problem the inventors recognized with the thin adhesive strips is that the adhesive bond between the grid and the underlying surface is not very strong. As the grid is intended to remain on the skin temporarily, perhaps a few hours at most, the adhesive is of a type that allows the grid to be removed fairly easily. Accordingly, the grid is susceptible to inadvertent movement such as sliding on the skin or detaching from the skin, thereby causing inaccuracies in the marked locations. Such inaccuracies increase the likelihood of having to repeat at least part of a procedure, such as, for example, a CT-guided biopsy, resulting in wasted time and materials, and more importantly, undue pain and discomfort for a patient.
It is an object of the present invention to overcome one or more of the above-described drawbacks and/or disadvantages of the prior art marking grids.